Various imaging techniques have been developed for the investigation of biological and other specimens. Some of these techniques (for example, magnetic resonance imaging and positron emission tomography) have become routine in clinical applications. Most imaging techniques rely on particular specimen properties to produce image contrast. For example, magnetic resonance images can depend on specimen spin T1 or T2 relaxation times, or spin densities. Magnetic resonance imaging has also been applied to so-called functional imaging (functional MRI or fMRI) so that magnetic resonance images can be associated with specimen brain function related to blood flow or oxygenation and not merely with specimen structure. Unfortunately, most magnetic resonance imaging systems require application of very high magnetic fields (1 Tesla or more), and thus require expensive, complex magnets. In addition, these high magnetic fields are problematic for clinical measurements of other types, due to the undesirable effects of large magnetic fields on other instrumentation that might be necessary for specimen measurements. In addition, while such magnetic resonance imaging methods generally have spatial resolution on the scale of millimeters (mm), they have poor temporal resolution, typically, no better than a few seconds. However, imaging methods in clinical and other applications can typically be selected to provide high spatial resolution images that lack high temporal resolution dynamic functional information, or to provide high temporal resolution functional information that cannot be readily associated with any specimen features or locations. Unfortunately, the use of magnetic resonance imaging in combination with other clinical measurement techniques is generally challenging, and improved methods and apparatus are needed.
Accordingly, aspects of the present invention can include a preferred system including an electrical impedance tomography apparatus electrically connectable to an object; an ultra low field magnetic resonance imaging apparatus including a plurality of field directions and disposable about the object; a controller connected to the ultra low field magnetic resonance imaging apparatus and configured to implement a sequencing of one or more ultra low magnetic fields substantially along one or more of the plurality of field directions; and a display connected to the controller. The controller can be further configured to reconstruct a displayable image of an electrical current density in the object. Additional aspects of the present invention can include a preferred method that includes delivering an electrical current through an object in a predetermined current direction; pulsing an ultra low magnetic field along one or more field directions; changing the direction of the ultra low magnetic field to another of the one or more field directions; detecting a resonance between the magnetic field associated with the applied electrical current and the nuclear spins within the ultra low magnetic field inside the object; and reconstructing an image of an electrical current density in the object in response to the detected resonance. In additional aspects of the present invention, the preferred system and method can be implemented at least in part in a distributed computing system and/or computer program product. These and other aspects, advantages, and salient features of the preferred embodiments of the present invention are described in detail below with reference to the following Figures.